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VOLATILITY OF INTERNAL-COMBUSTION ENGINE GASOLINE 210011

After stating that the meaning of the term “gasoline” seems to be generally misunderstood for the reason that it has been assumed that gasoline is, or ought to be, the name of a specific product, the author states that it is not and never has been a specific product and that although gasoline has a definite and generic meaning in the oil trade it has no specific meaning whatever. It means merely a light distillate from crude petroleum. Its degree of lightness, from what petroleum it is distilled and how it is distilled or refined are unspecified.

Specifically, “gasoline” is the particular grade of gasoline which at a given moment is distributed in bulk at retail. It can be defined with reasonable precision as being the cheapest petroleum product acceptable for universal use as a fuel in the prevailing type of internal-combustion engine. The author places emphasis on the three factors of this definition: (a) the cheapest product, (b) its universal use and (c) the prevailing type of internal-combustion engine.

The author's purpose in this paper is to clear away some of the haze which surrounds the word “gasoline” and with regard to what volatility is with reference to engine gasoline to show how much of the difficulty is inherent in the fuel and how much of it arises from the failure of automotive engineers, collectively, to attain a high average of perfection in the handling of the fuel to develop power.

Ordinary engine gasoline of the grade now sold possesses sufficient inherent volatility to take and maintain the condition of a gas at a temperature at or below average intake-manifold temperatures. Manifold condensation seldom, if ever, occurs and cylinder condensation is even less probable. The phenomena answering to these names are in fact mainly the visual evidences of the failure of the vaporizing device to function. Fuel once vaporized must stay in that condition; hence, if liquid is found beyond the vaporizer, it reached there as a liquid.

These conclusions are based on an examination of the fuel itself. The volumetric proportions of a combustible mixture are considered in detail in the paper and the physical meaning and measurement of volatility are fully discussed, tables of vapor-tensions being given and the special apparatus developed to determine the vapor-tension of gasoline being exhibited and described. Following this a full discussion of the requirements for full utilization of inherent volatility is presented, the conclusion reached being that the problem resolves itself into the further development, improvement and wider use of the hot-spot.